1. Abstract:
A series of NaLnI4O12 (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) have been
synthesized hydrothermally using various lanthanide, iodate, and sodium sources. The structures of
each analog were determined using single-crystal x-ray diffraction and found to be isostructural to
NaYI4O12. Crystallographic data (MoKα, λ=0.71073Å) of NaGd(IO3)3, a = 31.2446(18)Å, b =
5.5749(3)Å, c = 12.6040(7), β = 90.981(1), V = 2195.1(2) Z = (8), R(F) = 1.33% for 326 parameters
with 2765 reflections. NaLnI4O12 are also characterized using UV-Vis spectroscopy and Fluorescence
spectroscopy.
Introduction:
Transition metal and rare earth metal iodates have been of great interest in materials science due
to noncentrosymmetric (NCS)3, SHG4-5
, nonlinear-optical (NLO) properties,1
and magnetic
properties.2
The lone-pair in the I(V) within iodate systems creates asymmetric geometry responsible
for unusual structures. Compounds containing these Iodates with active lone-pair electrons can be
utilized as new SHG materials for lasers.4
Transition metal (TM) cations with d0
electron
configurations are widely explored due to strong SHG responses.5
Three iodate systems with d0
TM
cations that have been heavily studied are A-Ti/Zr-I(V)-O, A-V/Nb/Ta-I(V)-O, and A-Cr/Mo/W-I(V)-O
where A represents an alkali metal, alkaline earth, lanthanide (III) or silver ions.5
Aside from transition metals being the central metal in these iodate systems, lanthanide iodates
have been getting much attention in research because of their limited solubilities, which can be used in
radioactive chemical separations and depositions, and their potentiality to create NCS structures with
interesting magnetic and electric properties.2
By synthesizing the lanthanide analogs of the previously
reported NaYI4O12,6
its properties can now be compared to the lanthanide and maybe even actinide
analogs. Properties of non-radioactive lanthanides are usually studied first before similar methods are
performed with actinides for safety reasons when handling highly radioactive actinides such as Pu, Am,

2. and Cm.8
NaLnI4O12 (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) have been synthesized
hydrothermally, and their structures determined using single-crystal x-ray diffraction methods. Each
product produced plate rod crystals of different colors depending on which lanthanide is incorporated.
The Nd and Ho analogs exemplify the alexandrite effect. (This phenomena is caused by having several
narrow absorption bands as oppose to less number of broad bands.7(needs UV-Vis data for evidence))
Experimental Section:
Materials:
Gd(NO3)3 ∙ xH2O (99.9%, Alfa Aesar), Eu(NO3)3 ∙ xH2O (99.99%, Alfa Aesar), ErF3 (Anhydrous,
Trona American Potash & Chemical Corporation), SmF3 ( Anhydrous, Trona American Potash &
Chemical Corporation), NdF3 (Anhydrous, Alfa Aesar), Tb2O3 (99.9% Aldrich), Dy2O3 (99.9% Aldrich)
were used as received without further purification. Yb2O3 (99.9%, Aldrich), Ho2O3 (99.9%, Aldrich),
were reacted with concentrated HNO3 (69-70%, BDH) to dissolve the oxide form and then further
reacted with NaIO4 (99%, Arcos Organics) to synthesize the desired product. Distilled millipore filter
water were used in the synthesis of all crystals.
Synthesis:
Three different methods were used to synthesize NaLnI4O12.
Method (1): Ln(NO3)3 (Ln = Eu, Gd) ~100mg and NaIO4 ~800mg were combined with 7mL H2O and
are placed in a 23mL Teflon-lined autoclaves and were sealed. These autoclaves were heated to 200ºC
for three days and allowed to cool to room temperature. The products were recovered into a petri dish
and washed with H2O and ethanol and are allowed to dry. Colorless crystals were obtained from the
reaction that had colorless mother liquor. (% yields?)

3. Method (2): LnF3 (Ln = Nd, Sm, Er) ~ 55mg were combined with ~750mg of H5IO6, ~ 250mg of
NaIO4 and 3mL of H2O were placed in a 23mL Teflon-lined autoclaves and were sealed. These
autoclaves were heated to 200ºC for three days and allowed to cool to room temperature. The products
were recovered into a petri dish and washed with H2O and ethanol and are allowed to dry. The
autoclave containing the Nd produced sky blue crystals that exemplified the Alexandrite effect under
tungsten lamp and changed colors from sky blue to pale pink. The autoclave containing Sm produced
pale yellow crystals. Erbium produced light pink crystals.
Method (3): Ln2O3 (Ln = Tb, Dy, Ho, Tm, Yb, Lu) ~60mg were combined with ~1g of HIO3, ~60mg of
Na2CO3 and 2.5mL H2O and were placed and sealed inside a 23mL Teflon-lined autoclaves. The
autoclaves were heated to 220ºC for four days and allowed to cool to room temperature. The products
were recovered into a petri dish and washed with H2O and ethanol and are allowed to dry. Garnet
crystals were collected from the autoclave containing the Tb from a colorless mother liquor. The
autoclave containing Dy had white crystal rods in the colorless mother liquor. Pink crystals were
obtained in the vessel containing Ho and had light pink mother liquor. Colorless crystals were collected
from the autoclave containing the Yb source.
Discussion and Results:
NaGdI4O12 is a two-dimensional layered structure that exhibits a non-centrosymmetric crystal structure
in the monoclinic C space group cc. In each layer, a GdO8 polyhedra is bonded to IO3 and IO4 ligands
with two Na+
ions between each sheets. The central Gd3+
is bonded to eight bridging oxygens creating
a Square anti-prismatic structure with bond distances ranging from 2.314Å to 2.400Å. The bridging
oxos connect the central Gd3+
with the I5+
ions. The I5+
cations are bonded to either three or four
oxygen atoms. SOJT caused by the active lone-pair within the I(V) atom is responsible for the distorted
polyhedra containing the central Gd atom. The IO4 group exhibits one long I-O bond length ranging

4. from 2.425Å to 2.458Å while all the other I-O bonds within the structure range from 1.792()Å to
1.834()Å. (How does the long I-O bond affect the shape?) The long I-O bonds and its environment
results in the elongated a axis of 31.2446Å. The connectivity between the GdO8, IO3, and IO4
polyhedra creates a ring channel that can be seen along the b axis where the Na+
cations resides. This
topology closely resembles that of reported NaYI4O12 (needs citation) where an eight member ring
channel is present on each sheet. (More on bond-valance)
Things to do:
UV/Vis on Nd, Eu, Tb, Ho
Fluorescence on Eu, Tb
Raman on any one to show bond connectivity
Raymond script (Shape8) on metal centers
Crystal maker for shapes/figures
3 Ok KM.; Halasyamani PS. Chem. Soc. Rev. 2006, 35, 203-243
1 Lin W.; Lin, W.; Wpng, G. K.; Marks, T. J. J. Am. Chem. Soc. 1996, 118, 8034
2 Sykora R.; Khalifah P.; Assefa Z.; Albrecht-Schmitt T.; Haire Richard.; J. Solid State Chem. 2008, 181, 1867-1875
4 Phanon D.; Gautier-Luneau I. Angew. Chem. Int. Ed. 2007, 46, 8488-8491
5 Sun C.; Yang B.; Mao J.; Science China, Chem. 2011, 54, 911-922
6 OK KM.; Halasyamani PS. Inorg. Chem. 2005, 44, 9353-9359
8 Polinski M.; Grant D.; Wang S.; Alekseev E.; Cross.; Villa E.; Depmeier.; Gagliardi.; Albrecht-Schmitt T. J. Am. Chem.
Soc., 2012, 134 (25) 10682-10692
7 Bernstein L. American Mineralogist. 1982, 67, 356-359